CN102330144A - Preparation method and equipment of finished product large area seed crystal and rectangle large area seed crystal - Google Patents
Preparation method and equipment of finished product large area seed crystal and rectangle large area seed crystal Download PDFInfo
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- CN102330144A CN102330144A CN201110300537A CN201110300537A CN102330144A CN 102330144 A CN102330144 A CN 102330144A CN 201110300537 A CN201110300537 A CN 201110300537A CN 201110300537 A CN201110300537 A CN 201110300537A CN 102330144 A CN102330144 A CN 102330144A
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Abstract
The invention discloses a preparation method and equipment of a large-area seed crystal used for single crystal ingot casting. The preparation method comprises the following concrete steps of: 1) cutting off the top and the tail of a selected conventional {100} monocrystal rod, and splitting along a longitudinal surface (010) or (110) of a centre shaft to obtain single crystal seed crystal strips in a flat strip shape; 2) placing the single crystal seed crystal strips and a silicon material into a rectangle flat bottom crucible, and placing the rectangle flat bottom crucible into a horizontal growth furnace to carry out horizontal oriented growth, so as to obtain the finished product large area single crystal; and 3) cutting and polishing the obtained finished product large area single crystals to obtain the rectangle large area seed crystal used for carrying out single crystal ingot casting in an ingot casting furnace, wherein the side length of the rectangle large area seed crystal is 300-2000mm. By the method and equipment in the invention, the problem that the large area seed crystal is required for casting a single crystal is solved, and a technological foundation is provided for casting a single crystal silicon ingot, thereby crossing a 'quasi-single-crystal' or 'like-single-crystal' ingot casting technology.
Description
Technical field
The invention belongs to solar energy power generating (Photovoltaic) field, and relate to the method and apparatus of the silicon single-crystal ingot casting that is used for the photovoltaic industry, be specifically related to the preparation method and the equipment of a kind of finished product big area seed crystal and rectangle big area seed crystal.
Background technology
Green, environmental protection, continuable solar energy power generating have obtained fast development in recent years; See from the industry angle; The battery sheet that adopts crystal pulling method silicon single crystal and casting polycrystalline silicon to manufacture at present dominates in industry; And this wherein the polycrystalline silicon crystal cell become the center of gravity of industry development, occupied 54% photovoltaic market in 2010.Polysilicon chip is a main raw material of making the polycrystalline silicon crystal cell; Generally be in polycrystalline furnace, to obtain polycrystal silicon ingot in the industrial production through directional freeze; Evolution section obtains polysilicon chip and compares polycrystalline silicon ingot casting with pulling single crystal to have output big then; The advantage that cost is low, but there is a large amount of grain boundary dislocations in the polysilicon chip, the impurity effect in crucible and releasing agent during ingot casting simultaneously; Make the efficiency of conversion of polycrystalline silicon crystal cell than low 1～2% (absolute efficiency) of silicon single crystal, visible silicon ingot quality has direct influence to battery efficiency.
The ingot casting technology that generally uses in the industry at present is a directional solidification method, or claims that " heat-exchanging method ", its notable feature are that well heater is equipped with in crucible top and side; Crucible bottom is a cooling mechanism; Open cooling mechanism after the silicon material melts and carry out the original position directional freeze in flat crucible, the crystallization of bottom elder generation, the solid-liquid plane is moved on slowly then; Long from the bottom up crystalline substance is until all melts crystallization.Because initial nucleation crystalline is a stochastic process that occurs in crucible bottom simultaneously; There is not seed crystal; So grain size and crystal orientation all are unordered, therefore the silicon ingot that on these crystal grain, grows also is polycrystalline, and the size of columnar grain directly is decided by primary crystallization with distributing.The whole silicon ingot that grows up to is square, and the length of side has two kinds of 690mm and 825mm, and height is about 300～450mm, and weight is at 240～600kg.The at present up-to-date 1000mm length of side of developing can cast out the G6 ingot furnace of 1 ton of heavy silicon ingot.But the configuration of all these its thermal fields of ingot furnace does not have essential difference.Because well heater is at side and top; So be that the crucible upper temp is greater than the crucible bottom all the time in the whole ingot casting process; Under the condition that the silicon material of middle and upper part melts fully, guarantee the silicon material partial melting of bottom, make remaining grow big crystal grain silicon ingot as seed crystal and become possibility.If we transform this part silicon material of bottom wittingly, spread the monocrystalline silico briquette of bulk in the bottom, just can grow the big crystal grain silicon ingot that suits the requirements.
Utilizing existing polycrystalline ingot casting furnace superintendent monocrystalline or big crystal grain silicon ingot to have repeatedly attempts; The bottom graphite radiating piece of existing polycrystalline ingot furnace; The quartz ceramic crucible bottom all is flat, " type monocrystalline " or " accurate monocrystalline " so existing producer all grows through spread the multiple signle crystasl seed crystal in crucible bottom.These seed crystals generally all are the silico briquettes that the silicon single crystal rod of 6 cun or 8 cun blocks into thick 2～5cm.Numerous scientific research institutions and producer carried out aspect the class single crystal casting further investigation and applied for related patent U.S. Patent No., like BP Solar, Zhejiang University silicon materials laboratory, brilliant Australia, illuminate brightness, LDK etc.Each producer is different to this technological appellation, and " accurate monocrystalline ", " type monocrystalline ", " near monocrystalline " etc. are arranged.This technology has a bright future in the photovoltaic industry, has got into the pilot scale stage in batches.
Though the method for a plurality of seed crystals of this tiling can grow crystal grain very big " type monocrystalline ", wherein a spot of crystal boundary possibly become the convergence ground of impurity on the contrary, and the yield of follow-up battery sheet is exerted an influence.Simultaneously, because the silicon chip that this crystal-cut goes out still contains a certain amount of crystal boundary, still belong to polycrystalline.The present invention is applied to the ingot casting monocrystalline, has crossed over " type monocrystalline " these a kind of intermediates.
Summary of the invention
The objective of the invention is to overcome the shortcoming of above-mentioned prior art, preparation method and the equipment of a kind of monocrystalline ingot casting with the big area seed crystal are provided, this preparation method can prepare the big area monocrystalline; Be used for photovoltaic industry polycrystalline ingot casting and can grow silicon single crystal ingot; The silicon single crystal ingot that grows through ingot casting obtains monocrystalline silicon piece after section, this monocrystalline silicon piece not only has all character of CZ vertical pulling method silicon single crystal, and output is big and cost is low; And can also solve the high shortcoming of oxygen level in the vertical pulling method silicon single crystal
The objective of the invention is to solve through following technical scheme:
This kind monocrystalline ingot casting may further comprise the steps with the preparation method of finished product big area monocrystalline:
1) get the 100} single crystal rod is clipped end to end, along axis vertically (010) or (110) face cut the single crystal seed bar that obtains flat strip open;
2) prepare the flat crucible of rectangle; Coat release layer at the flat crucible internal layer of rectangle; Again described single crystal seed bar is placed in the flat crucible of rectangle; And make its parallel one side that abuts against at the bottom of the flat crucible of rectangle, polycrystalline silicon material is spread in remaining space of crucible bottom, puts into the horizontal growth stove then and carries out the horizontal orientation growth; Adopting Horizontal Gradient Freezing or Horizontal Bridgeman method to make polycrystalline silicon material fusing back is the substrate directional freeze with the single crystal seed bar, solidify direction from one side that the flat crucible of rectangle is placed the single crystal seed bar to opposite side; Growth method is: the heating polycrystalline silicon material makes its fusing earlier; And make the single crystal seed bar be in cold zone, it is not melted or fusing on a small quantity; Controlling thermal field then forms on the solid-liquid interface between molten silicon liquid and the single crystal seed bar and keeps a thermograde; Its direction is pointed to silicon liquid and perpendicular to solid-liquid interface; Size is between 2.6～21.2K/cm, and this moment, the rest part temperature of silicon liquid was on the fusing point; Thermograde makes heat conduct to the single crystal seed bar from silicon liquid, and the single crystal seed bar is constantly grown, and all silicon liquid become the solid silicon monocrystalline at last, through cooling to room temperature gradually after the annealing between 1300～1400 ℃, obtains finished product big area monocrystalline again; Whole growth process is carried out in the high-purity argon gas atmosphere, and air pressure is between 50mbar～600mbar.
Further, in described growth method, heating polycrystalline silicon material temperature is 1440～1560 ℃; The cold zone temperature of placing said single crystal seed bar is less than 1420 ℃ silicon fusing point; The thickness of said finished product big area monocrystalline is 10～60mm.
Further; In above step 2) in, before placement single crystal seed bar advances in the flat crucible of rectangle, said single crystal seed bar head and the tail two ends are polished into the shape that adapts with the flat crucible bottom chamfering of said rectangle; And the stupefied line in bottom surface and the base in the flat crucible of rectangle of single crystal seed bar is fitted; This moment the single crystal seed bar aufwuchsplate, vertical with thermograde, the crystal orientation is < 100>or < 110 >.
The thickness of above-mentioned single crystal seed bar is 10～60mm, width＞10mm, and length is 300～2000mm; The aufwuchsplate of said single crystal seed bar is (100) or (110).
Above-mentioned steps 2) the flat crucible of rectangle that uses in is flat shallow mouthful of crucible, and its length of side is between 300～2000mm, and the bottom transverse cross-sectional shape on its width is identical with foundry furnace crucible bottom xsect; The material of the flat crucible of described rectangle is quartz, fused quartz ceramic or graphite.
The present invention also proposes a kind of purposes of above-mentioned finished product big area monocrystalline: described finished product big area monocrystalline is cut and polishes; Be used for the preparation that ingot furnace carries out the rectangle big area seed crystal of single crystal rod growth, the said rectangle big area seed crystal length of side is between 300～2000mm.
The present invention utilizes the method for finished product big area single crystal preparation rectangle big area seed crystal, may further comprise the steps:
(1), the big area monocrystalline is cut into the rectangle big area monocrystalline of square or other suitable crucibles of 690mm or the 825mm or the 1000mm length of side with silicon carbide band saw or silicon carbide abrasive scroll saw excision finished product big area monocrystalline edge redundance;
(2) polishing rectangle big area monocrystalline makes it consistent with polycrystalline silicon ingot casting crucible bottom surface shape, uses the acid solution cleaner surface at last again, obtains being used for the rectangle big area seed crystal of monocrystalline ingot casting.
A kind ofly be used to realize the horizontal growth stove of above-mentioned monocrystalline ingot casting: many group well heaters are arranged in the stove, place the flat crucible of rectangle in the middle of the well heater with the preparation method of finished product big area monocrystalline.Thereby the thermograde that the horizontal growth stove can produce in the horizontal direction realizes that horizontal orientation solidifies.The below of said horizontal growth stove is provided with crucible and supports, and it is to constitute the parallel shape structure of deleting with many rectangular slabs of stone ink-stick that said crucible supports.
Compared with prior art, the present invention has following beneficial effect:
The present invention makes the possibility that creates of big area monocrystalline; Be used for photovoltaic industry polycrystalline ingot casting and can grow proper silicon single crystal ingot; The silicon single crystal ingot that grows through ingot casting obtains monocrystalline silicon piece after section; This monocrystalline silicon piece not only has all character of traditional C Z vertical pulling method silicon single crystal, has its incomparable big output and low-cost advantage, can also solve the high shortcoming of oxygen level in the vertical pulling method silicon single crystal easily; And elevated oxygen level is to cause the silicon single-crystal battery to produce the reason of photic efficient decay; Therefore cast out monocrystalline and also have, improve final battery efficiency from another angle than the low advantage of CZ vertical pulling method photo attenuation. simultaneously, the silicon chip made from this silicon single crystal ingot is to be formed by square ingot evolution section; Avoid tradition and lifted the assembly that circular big chamfering that the silicon rod butt stays caused and show money or valuables one carries unintentionally, improved battery component efficient (about 4～5%).The present invention makes photovoltaic module can accomplish lower cost in future, has huge economic.
Description of drawings
Fig. 1 is a single crystal seed bar cutting synoptic diagram;
Fig. 2 is the dress crucible method of seed crystal and silicon material;
Fig. 3 is two kinds of special horizontal growth stove signals;
Fig. 4 is that ingot casting is with quartz ceramic crucible and flat shallow mouthful of crucible bottom xsect;
Fig. 5 is a special crucible profile among the embodiment 2;
Fig. 6 is the palisade graphite pallet of support crucible.
Embodiment
Monocrystalline ingot casting of the present invention specifically may further comprise the steps with the preparation method of big area seed crystal:
1) as shown in Figure 1, get the 100} single crystal rod is clipped end to end, and along axis vertically (010) or (110) face cut the single crystal seed bar that obtains flat strip open; The thickness of said single crystal seed bar is 10～60mm, width＞10mm, and length is 300～2000mm.
2) as shown in Figure 2; Prepare the flat crucible of rectangle; Coat release layer (can be spraying silicon nitride figure layer) at the flat crucible internal layer of rectangle, more described single crystal seed bar 1 is placed in the flat crucible 3 of rectangle, and make its parallel one side that abuts against at the bottom of flat crucible 3 crucibles of rectangle; Before placement single crystal seed bar 1 advances in the flat crucible 3 of rectangle; Said single crystal seed bar 1 head and the tail two ends are polished into the shape that adapts with flat crucible 3 bottom chamfer of said rectangle, and the bottom surface of single crystal seed bar 1 and the stupefied line in base in the flat crucible 3 of rectangle are fitted, the crystal orientation of the aufwuchsplate (with the vertical plane of thermograde) of single crystal seed bar is < 100>or < 110>at this moment; Spread polycrystalline silicon material 2 in remaining space, rectangle flat crucible 3 bottoms then; Put into the horizontal growth stove then and carry out the horizontal orientation growth; Adopting Horizontal Gradient Freezing or Horizontal Bridgeman method to make polycrystalline silicon material fusing back is the substrate directional freeze with the single crystal seed bar; Solidify direction from one side that the flat crucible of rectangle is placed the single crystal seed bar to opposite side, the aufwuchsplate of single crystal seed bar is (100) or (110).Growth method is: the heating polycrystalline silicon material makes its fusing earlier, and Heating temperature is 1440～1560 ℃; Make the single crystal seed bar be in cold zone, this cold zone temperature does not melt it or fusing on a small quantity less than 1420 ℃ silicon fusing point; Controlling thermal field then forms on the solid-liquid interface between molten silicon liquid and the single crystal seed bar and keeps a thermograde; Its direction is pointed to silicon liquid and perpendicular to solid-liquid interface; Size is between 2.6～21.2K/cm, and this moment, the rest part temperature of silicon liquid was on the fusing point (promptly 1425～1480 ℃); Thermograde make heat from silicon liquid to the transmission of single crystal seed bar, the single crystal seed bar is constantly grown, all silicon liquid become the solid silicon monocrystalline at last, again through between 1300～1400 ℃ annealing after cool to room temperature gradually, obtain finished product big area monocrystalline.Whole growth process is carried out in the high-purity argon gas atmosphere, and air pressure is between 50mbar～600mbar.The present invention proposes a kind of finished product big area monocrystalline that will obtain and cuts and polish, and is used for the preparation that ingot furnace carries out the rectangle big area seed crystal of single crystal rod growth, and the said finished product big area seed crystal length of side is between 300～2000mm, and thickness is 10～60mm.
The Horizontal Gradient Freezing (HGF) that is mentioned in the foregoing invention technical scheme is the horizontal temperature gradient freezing method; The existing vertical gradient freeze technique of AXT Inc. is that Vertical Gradient Freezing (VGF) only is used to produce the single crystal rod less than 6 inch diameters such as high-quality gallium arsenide, indium phosphide, germanium; This system is made up of the well heater of a vertical tubular type furnace chamber and a plurality of discrete controls; No mechanical moving parts in the stove, the accurate control growing interface temperature of each heater power gradient is constant to be shifted to the top gradually from the seed crystal end and accomplishes crystal growth to reach aufwuchsplate through changing.Because the characteristic of volumetric expansion after the silicon condensation, VGF is not suitable for large diameter silicon monocrystal growth.Horizontal growth temperature of the present invention control is similar with the Vertical Temperature control that is VGF, but uses crucible and global design etc. to be different from VGF fully, therefore continues to use the appellation of temperature gradient solidification in the present invention and is named as HGF.
Horizontal Bridgeman method in the technical scheme of the present invention is that the horizontal Bridgman method arsenicization that mainly is used for growing such as sows at compound monocrystal; System is made up of a tube furnace and haulage gear; It is characterized in that the tube furnace molten material and unidirectional temperature field is provided; And near growth interface, form negative temperature gradient, and seed crystal places an end, and crystal growth can be carried out through mobile crucible or stove.Its core is the variation realization directional freeze that produces thermograde through the relative displacement of thermal field and crucible.Be used to before the crystal growth of horizontal Bridgman method the to grow compound monocrystal of small dia, typical sizes have 2 inches, 4 inches etc.Body of heater among the present invention is a flats, the growth plane rectangle that is as the criterion, and width reaches 690～1000mm, is the new application of this method in silicon single-crystal ingot casting field.
The material of the flat crucible of rectangle that uses the step 2 of above technical scheme of the present invention) is quartz, fused quartz ceramic or graphite.It is flat shallow mouthful of crucible, and the length of side is between 300～2000mm, and the bottom transverse cross-sectional shape on the width is identical, as shown in Figure 4 with foundry furnace crucible bottom xsect.
In order to realize above-mentioned preparation method, the present invention has also designed special-purpose horizontal growth stove targetedly, and like Fig. 3, this horizontal growth stove comprises well heater, thermofin, graphite base plate, the flat crucible of rectangle etc.; A plurality of well heaters are arranged, the middle flat crucible of rectangle of placing in the stove.Thereby the thermograde that the horizontal growth stove can produce in the horizontal direction realizes that horizontal orientation solidifies.Structure can have two kinds; A kind of is Horizontal Gradient Freezing method (like Fig. 3 b); It is characterized in that utilizing a plurality of well heater b1-b19, the b20 of independent control to make the thermograde zone move with crystal growth interface and move; Do not have the mechanical part motion during growth, wherein a plurality of well heater b1-b19, b20 are the heating unit of discrete control, and the heating gradient direction is parallel to the X axle and points to silicon liquid; Another kind is Horizontal Bridgeman method (shown in Fig. 3 a); It is characterized in that using flat crucible 3 is placed on the guide rail 4; Utilize guide rail 4 that the flat crucible 3 of rectangle is slowly pulled out the high-temperature zone, two groups of heating units forming to well heater as+1 by well heater a1 at the upper and lower sides of the flat crucible 3 of rectangle.The present invention adopts high-performance insulation material thermal insulation layer 5 to comprise the whole thermal field of well heater and crucible, and its outside is the water cooled furnace wall.And below horizontal growth stove of the present invention, be provided with crucible and support, as shown in Figure 6, it is to constitute the parallel shape structure of deleting with many rectangular slabs of stone ink-stick that this crucible supports.
The present invention also cuts described finished product big area monocrystalline and polishes; Be used for the rectangle big area seed crystal that ingot furnace carries out the single crystal rod growth; The length of side of the rectangle big area seed crystal of preparation is between 300～2000mm, and the method that this prepares rectangle big area seed crystal specifically may further comprise the steps:
(1) also can downcut the single crystal seed bar of several monocrystalline bars with silicon carbide band saw or silicon carbide abrasive scroll saw excision big area monocrystalline edge redundance as next big area single crystal growing; The big area monocrystalline is cut into the rectangle big area monocrystalline (in most preferred embodiment of the present invention, the big area monocrystalline being cut into the rectangle big area monocrystalline of 690mm or the 825mm or the 1000mm length of side) that shape is fit to the polycrystalline silicon ingot casting crucible;
(2) polishing rectangle big area monocrystalline makes it consistent with polycrystalline silicon ingot casting crucible bottom surface shape, uses the acid solution cleaner surface at last again, obtains being used for the rectangle big area seed crystal of monocrystalline ingot casting.
Below in conjunction with embodiment and accompanying drawing the present invention is done and to describe in further detail:
6 cun single crystal rod in < 100>crystal orientation that vertical pulling method is obtained tail of decaptitating, obtaining length is the isometrical silicon rod of 825mm, reserves the crystal orientation with laser; With silicon rod in the band saw upper edge (010) crystal face through the axis cut open, two parallel sections obtain thick 40mm apart from each 20mm of axis; Long 825mm; The long seed crystal bar of the monocrystalline of wide about 150mm, with this seed crystal bar again along center line to cuing open, obtain the wide seed crystal bar of 75mm that is; Again these seed crystal bar head and the tail two ends are polished into the shape of the flat crucible bottom edge chamfer of rectangle, so that can put into flat crucible, this moment, the positive crystal orientation of this seed crystal bar 40 * 825 was (100).
Length of side 900mm in getting, the outer length of side 920mm of wide 825mm, wide 845mm; The quartz ceramic crucible of high 70mm; The crucible internal layer is coated with silicon nitride figure layer, places the silicon material in crucible bottom, and this single crystal seed bar is put into crucible one side; Spread the polycrystalline silicon material of 47.6kg in remaining space of crucible bottom, the amount of 47.6kg silicon material is to calculate in advance to make the big area monocrystalline thickness of finished product just in time be 30mm.
The crucible that above-mentioned silicon material is housed is placed ingot furnace 3a, earlier crucible seed crystal bar end is placed during placement and take out mouthful (or thermal field) outside, the crucible major part is in the thermal field and an end of putting the seed crystal bar at the thermal field cold zone; Well heater is limited to the heats of this end; Vacuumize and open a1, a2 ... heater heats; Feed argon gas when temperature reaches 1200 ℃ in the thermal field by the time and do not decompose, after this keep ar pressure at 200mbar with protection silicon nitride figure layer.Treat that temperature rises to 1500 ℃, when crucible places most of silicon material of thermal field to be molten into liquid state, again crucible is slowly moved into the hot-zone along the x negative direction; Simultaneously slowly be cooled to 1450 ℃, rate of temperature fall is 0.5 ℃/min, makes remaining silicon material fusing; And slowly to as; As+1 ... well heater adds power, and the thermopair that makes well heaters such as as be close to remains on 1425 ℃.From the fusing situation of top vision slit close attention seed crystal, when the seed crystal fusing 15mm left and right sides, reduce a1, a2; ... power, inner temperature of thermal field is remained on about 1440 ℃, reduce cold zone as simultaneously; As+1... power; Make the cold zone temperature maintenance about 1380 ℃, slowly at the uniform velocity crucible is pulled out along the x positive dirction, speed is 2cm/h.
When crucible is pulled out the high-temperature zone, after vision slit is observed crystal growth and finished fully, crucible is pushed the high-temperature zone along the x negative direction once more, reduce heater power and make temperature in the high-temperature zone remain on 1390 ℃ to anneal 2 hours, and let crystal slowly cool off later.
Cooled crystal takes out from crucible, under the silicon carbide band saw, will connect the long single crystal rod of the common 950mm of seed crystal and be cut into the square silicon ingot of 825mm, and the 110mm under cutting still can use as seed crystal next time.Can pack into the ingot casting crucible of normal 825*825*420mm of the chamfer radius that the lower edge of the silicon ingot edge of a knife is polished into crucible uses as (100) crystal face big area single crystal seed.
8 cun single crystal rod of heavily doped boron in < 100>crystal orientation that vertical pulling method is obtained tail of decaptitating, obtaining length is the isometrical silicon rod of 825mm.Reserve the crystal orientation with laser, with silicon rod in axis, band saw upper edge radially (110) cut open, two parallel sections obtain thick 50mm apart from each 25mm of axis, long 825mm, the long seed crystal bar of the monocrystalline of wide about 200mm.This seed crystal bar is cut open along the center line trisection again, obtained three of wide seed crystal bars for 60mm.This moment, the aufwuchsplate of this seed crystal bar 50 * 825 was (110).
Length of side 900mm in getting, the outer length of side 920mm of wide 825mm, wide 845mm, the special quartz ceramic crucible of high 80mm.Do not have chamfering (like Fig. 5) in the scope of one side base of this crucible and two adjacent base 6cm length, therefore the corresponding seed crystal of putting into also need not chamfering.The crucible internal layer is coated with silicon nitride figure layer, places silicon material and crucible adhesion.This single crystal seed bar is put into special crucible one side, spread the polycrystalline silicon material of 64.6kg in remaining space of crucible bottom, the amount of 64.6kg silicon material is to calculate in advance to make the big area monocrystalline thickness of finished product just in time be 40mm.
The crucible that above-mentioned silicon material is housed is placed ingot furnace 3b, vacuumize and open b1～b20 heater heats, feed argon gas when temperature reaches 1200 ℃ in the thermal field by the time and do not decompose with protection silicon nitride figure layer; Keep ar pressure at 200mbar, open thermoswitch b21 simultaneously, strengthen the heat radiation of seed crystal side; Treat that temperature slowly rises; Well heater begins independent control side by side, makes the temperature of seed crystal side be controlled at 1425 ℃ and opposite side can reach 1500 ℃, and the silicon material away from seed crystal in the crucible at first melts; Slowly extend then to seed crystal one side; Finely tune each heater power control silicon and anticipate to fusing, finally molten silicon begins to touch seed crystal, and this moment, remaining silicon material all melted.Keep a close eye on the fusing situation of seed crystal from top vision slit; When the seed crystal fusing 20mm left and right sides, reduce b19 rapidly, b20 power drops to about 1380 ℃ b20; B19 drops to about 1400 ℃; The corresponding well heater of crucible top also carries out similar operations, and other heater temperatures are maintained about 1435 ℃, and it is substrate grown that silicon is begun with the seed crystal.Thereafter the power that process reduces well heater one by one by certain algorithm constantly moves temperature gradient field to x axle negative direction under the constant situation of size.
After vision slit is observed crystal growth and is finished fully, close thermoswitch, start institute's having heaters and make each point temperature in the thermal field remain on 1370 ℃ to anneal 2 hours.Later stopping heating letting crystal slowly cool off.
Cooled crystal takes out from crucible, under the silicon carbide band saw, will connect the long single crystal rod of the common 900mm of seed crystal and be cut into the square silicon ingot of 825mm, and the 60mm under cutting still can use as seed crystal next time.Can pack into the ingot casting crucible of normal 825*825*420mm of the chamfer radius that the lower edge of the silicon ingot edge of a knife is polished into crucible uses as the substrate of (110) crystal face big area single crystal seed.
Claims (9)
1. the preparation method of a finished product big area monocrystalline is characterized in that, may further comprise the steps:
1) get the 100} single crystal rod is clipped end to end, along axis vertically (010) or (110) face cut the single crystal seed bar that obtains flat strip open;
2) prepare the flat crucible of rectangle; Coat release layer at the flat crucible internal layer of rectangle; Again described single crystal seed bar is placed in the flat crucible of rectangle; And make its parallel one side that abuts against at the bottom of the flat crucible of rectangle, polycrystalline silicon material is spread in remaining space of crucible bottom, puts into the horizontal growth stove then and carries out the horizontal orientation growth; Adopting Horizontal Gradient Freezing or Horizontal Bridgeman method to make polycrystalline silicon material fusing back is the substrate directional freeze with the single crystal seed bar, solidify direction from one side that the flat crucible of rectangle is placed the single crystal seed bar to opposite side; Growth method is: the heating polycrystalline silicon material makes its fusing earlier; And make the single crystal seed bar be in cold zone, it is not melted or fusing on a small quantity; Controlling thermal field then forms on the solid-liquid interface between molten silicon liquid and the single crystal seed bar and keeps a thermograde; Its direction is pointed to silicon liquid and perpendicular to solid-liquid interface; Size is between 2.6～21.2K/cm, and this moment, the rest part temperature of silicon liquid was on the fusing point; Thermograde makes heat conduct to the single crystal seed bar from silicon liquid, and the single crystal seed bar is constantly grown, and all silicon liquid become the solid silicon monocrystalline at last, through cooling to room temperature gradually after the annealing between 1300～1400 ℃, obtains finished product big area monocrystalline again; Whole growth process is carried out in the high-purity argon gas atmosphere, and air pressure is between 50mbar～600mbar.
2. the preparation method of finished product big area monocrystalline according to claim 1 is characterized in that, in described growth method, heating polycrystalline silicon material temperature is 1440～1560 ℃; The cold zone temperature of placing said single crystal seed bar is less than 1420 ℃ silicon fusing point; The thickness of said finished product big area monocrystalline is 10～60mm.
3. the preparation method of finished product big area monocrystalline according to claim 1; It is characterized in that; Step 2) in, before placement single crystal seed bar advances in the flat crucible of rectangle, said single crystal seed bar head and the tail two ends is polished into the shape that adapts with the flat crucible bottom chamfering of said rectangle; And the stupefied line in bottom surface and the base in the flat crucible of rectangle of single crystal seed bar is fitted, the crystal orientation of the aufwuchsplate of single crystal seed bar is < 100>or < 110>at this moment.
4. according to the preparation method of claim 1,2 or 3 described finished product big area monocrystalline, it is characterized in that the thickness of said single crystal seed bar is 10～60mm, width＞10mm, length is 300～2000mm; The aufwuchsplate of said single crystal seed bar is (100) or (110).
5. the preparation method of finished product big area monocrystalline according to claim 1; It is characterized in that; Step 2) the flat crucible of rectangle that uses in is flat shallow mouthful of crucible, and its length of side is between 300～2000mm, and the bottom transverse cross-sectional shape on its width is identical with foundry furnace crucible bottom xsect; The material of the flat crucible of described rectangle is quartz, fused quartz ceramic or graphite.
6. the purposes of the said finished product big area of claim 1 monocrystalline is characterized in that, described finished product big area monocrystalline is cut and polishes, and is used for the preparation that ingot furnace carries out the rectangle big area seed crystal of single crystal rod growth.
7. a method of utilizing finished product big area single crystal preparation rectangle big area seed crystal is characterized in that, may further comprise the steps:
(1) with silicon carbide band saw or silicon carbide abrasive scroll saw excision finished product big area monocrystalline edge redundance, the big area monocrystalline is cut into the rectangle big area monocrystalline that shape is fit to the polycrystalline silicon ingot casting crucible;
(2) polishing rectangle big area monocrystalline makes it consistent with polycrystalline silicon ingot casting crucible bottom surface shape, uses the acid solution cleaner surface at last again, obtains being used for the rectangle big area seed crystal of monocrystalline ingot casting.
8. a horizontal growth stove that is used to realize the said method of claim 1 is characterized in that, many group well heaters are arranged in (1) stove, places the flat crucible of rectangle in the middle of the well heater; (2) thus the horizontal growth stove can produce thermograde in the horizontal direction realizes that horizontal orientation solidifies.
9. horizontal growth stove according to claim 8 is characterized in that, the below of said horizontal growth stove is provided with crucible and supports, and it is to constitute the parallel shape structure of deleting with many rectangular slabs of stone ink-stick that said crucible supports.
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| CN103046129A (en) * | 2013-01-28 | 2013-04-17 | 天津英利新能源有限公司 | Polycrystalline silicon ingot casting process |
| WO2016123866A1 (en) * | 2015-02-05 | 2016-08-11 | 中国电子科技集团公司第二十六研究所 | Method for preparing large-sized slablike ce3+ ion doped rare-earth orthosilicate-series scintillation crystals by means of horizontal directional solidification |
| CN106367808A (en) * | 2015-07-24 | 2017-02-01 | 北京京运通科技股份有限公司 | Production method of silicon cores |
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| CN112590032A (en) * | 2020-12-03 | 2021-04-02 | 天津市环智新能源技术有限公司 | Solar silicon wafer and roughness control method thereof |
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| CN102653881A (en) * | 2012-04-20 | 2012-09-05 | 镇江环太硅科技有限公司 | Method for casting large-grained silicon ingot |
| CN102758243A (en) * | 2012-07-06 | 2012-10-31 | 无锡中硅科技有限公司 | Seed crystal of large-size single crystal and production process thereof |
| CN102808213A (en) * | 2012-08-21 | 2012-12-05 | 安阳市凤凰光伏科技有限公司 | Preparation method for large-area crystal seeds of similar single crystals produced by casting method |
| CN103046129A (en) * | 2013-01-28 | 2013-04-17 | 天津英利新能源有限公司 | Polycrystalline silicon ingot casting process |
| CN103046129B (en) * | 2013-01-28 | 2015-10-07 | 天津英利新能源有限公司 | Polycrystalline silicon casting ingot process |
| WO2016123866A1 (en) * | 2015-02-05 | 2016-08-11 | 中国电子科技集团公司第二十六研究所 | Method for preparing large-sized slablike ce3+ ion doped rare-earth orthosilicate-series scintillation crystals by means of horizontal directional solidification |
| CN106367808A (en) * | 2015-07-24 | 2017-02-01 | 北京京运通科技股份有限公司 | Production method of silicon cores |
| CN107523858A (en) * | 2017-07-26 | 2017-12-29 | 晶科能源有限公司 | A kind of seed crystal laying method, the casting method of class monocrystal silicon and class monocrystalline silicon piece |
| CN112590032A (en) * | 2020-12-03 | 2021-04-02 | 天津市环智新能源技术有限公司 | Solar silicon wafer and roughness control method thereof |
| CN113172777A (en) * | 2021-04-23 | 2021-07-27 | 深圳大学 | Detector-grade high-purity germanium single crystal seed crystal and preparation method and application thereof |
| CN113172777B (en) * | 2021-04-23 | 2022-10-04 | 深圳大学 | Detector-grade high-purity germanium single crystal seed crystal and preparation method and application thereof |
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